The invention relates to satellite communications and, more particularly, to a method and apparatus for processing multiple TDMA frames from multiple transponder downlinks.
A typical Satellite Communications Controller (SCC) has sufficient capacity to receive data from a single transponder only. However, as the use of satellite communications increases and satellites become increasingly loaded, it becomes necessary for communications networks to receive data from more than one transponder. Therefore, in order to utilize existing TDMA terminals in a multi-transponder mode, it is an object of the invention to provide an interface between the multiple transponders and the single SCC which will enable the SCC to process data as if it were receiving transmissions from just a single transponder. Preferably, the interface would appear to the SCC as if it were a modem and the use thereof would not require substantial modification to the terminal.
One known technique for engaging multiple transponders in a network is known as "transponder hopping." With transponder hopping, a plurality of stations acting in concert can transmit to or receive from more than a single transponder. The use of transponder hopping is discussed by Schmidt in his U.S. Pat. No. 4,115,661 which issued Sept. 19, 1978, and in his article "The Application of TDMA to INTELSAT IV Satellite Series" which appeared in the COMSAT Technical Review, vol. 3, no. 2, pages 257-75 (Fall 1973). Since one of the main characteristics of transponder hopping is that a plurality of terminals on one side of a downlink communicate with one another, with each of these terminals being able to receive only one downlink at a time, a high degree of burst scheduling must take place so that the communication can be orderly. It is therefore another object of the invention to provide a method of multiple transponder networking which does not require burst scheduling between earth terminals.